Ruby 2.7, the latest upgrade of the Ruby programming language, is now in a preview release. Ruby 2.7 brings improvements in garbage collection, pattern matching, and REPL (read-eval-print-loop).

The general release is planned for December 2019. New in the Ruby preview release is compaction garbage collection, which is used to defragment a fragmented memory space. The GC.compact method compacts the objects in the heap so that fewer pages are used. Members of the Ruby development team explained that some multi-threaded Ruby programs may cause memory fragmentation, which leads to high memory utilization and speed degradation.

Other improvements in Ruby 2.7.0 include:

An experimental pattern matching capability, which can traverse a given object and assign a value if it matches a pattern. Pattern matching is widely used in functional programming languages.

Multi-line editing is now supported in irb, the interactive Ruby shell. Integration with rdoc, the Ruby documentation system, also is provided. With irb, developers can display the reference for a class, method, or module. Also, source lines shown at binding.irb and inspect results for core-class objects now are colorized.

For the still-experimental just-in-time (JIT) compiler, , JIT-ed code is recompiled to less-optimized code when an optimization has been invalidated. Further, method inlining is performed when a method is considered pure. However, many methods are not yet considered pure.

An Enumerable#tally counts the occurrence of each element.

A method reference operator, .:, is included on an experimental basis.

Also introduced as an experimental feature is a numbered parameter as the default block parameter.

You can as well as stable releases of Ruby from .

Paul Krill is an editor at large at InfoWorld, whose coverage focuses on application development.